Glow plug module issues E320CDI - PeachParts Mercedes-Benz Forum

spark3542 · #1 03-30-2016, 01:35 PM

My recently purchased CDI came at a great price, but also came complete with CEL illuminated. P0670 and P0299. P0299 is turbo underboost, but today's question is about the P0670.

Doing a search on that, the general consensus is the glow plug module. I searched for a replacement, it appears that Beru makes the OE, but Dorman also makes it. The cheapest I found the Dorman 904-310 was about $130, and Beru was in the mid $200s. I opted for the Dorman. I plugged it in, and immediately got the CEL for p0683, which is communication from glow plug module to PCM.

I thought maybe I tugged too hard on the connector wiring, so I plugged the old Beru back in, get p0670 again...Return to the Dorman, get p0683.

Some said.. bad ground at the manifold. I checked that...it is solid and good connection to the ground pin on the connector.

BTW, glow plugs all ohm-out good, and car starts quick and smooth both warm and cold.

Has anyone else had problems with the Dorman's? I'll go ahead and spring for the Beru if that's the problem, but I'd like some confidence that that's the issue.

Diesel911 · #2 03-30-2016, 04:21 PM

Where was the Doman Relay made? Most of the Dorman stuff I have bought has been made in China.

Beyond that a Glow Plug can Ohm out OK and still be no good.

duxthe1 · #3 03-31-2016, 12:19 AM

Ive never installed a dorman relay so I cant speak directly to their quality but I'd be dubious.

I will tell you to measure the voltage on the high current lead when the relay is active. Good modules will give communication errors if the high current feed has issues causing voltage drop.

MB_FanAddict · #4 03-31-2016, 04:57 PM

It may be a perfectly fine relay, but the Doorman part only cross references the later V6 engines (642XXXXXXX).

648-135-02-79 is the current part number of the glow plug controller for the US (MY05/06) E320 CDI. The correct Beru part is GSE 113.

spark3542 · #5 04-01-2016, 09:28 AM

Thanks for the feedback. I guess there's some discrepancies in the cross-reference databases, because the Dorman was coming up as a fit.

Regardless, I'm going to try both the "suspect" Beru and new Dorman in my test fixture (i.e. my other CDI) to confirm the same codes this weekend. I'm paranoid that the real issue may be PCM wiring.

It's too bad that this module is such a pain in the a** to get to. It's under the intake manifold and above the starter. It appears in the alldata that some CDI's have the module mounted up top near the coolant tank, but neither of mine are like that.

spark3542 · #6 04-04-2016, 09:00 AM

Well, I plugged the suspect Beru unit into the other CDI. No codes, no extended glow lights, everything is normal.

That now suggests...the problem is wiring between module and PCM, PCM itself, or glow plugs.

Grrr.